1. Field of the Invention
The present invention relates to a robot system for carrying out laser processing by using a robot having a laser irradiation device, and a laser processing method using the robot system.
2. Description of the Related Art
As a system for carrying out laser processing by using a laser irradiation device, a laser processing robot system using a robot is well known. For example, JP 2007-098416 A discloses a laser welding device including: a robot; a laser irradiation means attached to the robot and adapted to irradiate a laser beam; a measurement means for measuring a current position of the robot; and a control means for controlling a direction of the laser beam irradiated from the laser irradiation means based on the current position measured by the measurement means, so that an irradiated position of the laser beam coincides with a predetermined position.
Further, JP 2012-139711 A discloses a laser processing unit including: a robot having a front end to which a laser scanner is attached; and a controller having a robot control system and a laser scanner control system.
In the technique of JP 2007-098416 A or JP 2012-139711 A, the laser irradiation device for irradiating the laser beam is attached to the front end of the robot arm, so that the laser irradiation device carries out welding, cutting or piercing, etc., by moving the robot arm and changing the irradiation direction of the laser beam from the laser irradiation device. The laser processing as such is also referred to as a remote laser, since the distance between the workpiece and the laser irradiation device is relatively large.
In the remote laser, the processing with high accuracy can be carried out, whereas the processing accuracy thereof depends on the motion accuracy of the robot, since the laser irradiation device is attached to the robot. For example, although JP 2007-098416 A discloses a means for correcting the irradiation position while measuring a three-dimensional position of the robot gripping the irradiation device in real-time, a control delay may occur in the real-time correction. In addition, it is necessary that the system always has a measurement device, and the same number of measurement devices as the systems are necessary. Further, if the measurement device has a trouble during use of the system, the irradiation position cannot be corrected.
On the other hand, the technique of JP 2012-139711 A is intended to avoid the control delay as in JP 2007-098416 A by previously simulating the robot motion. However, the simulation usually includes a certain level of error, and thus the error may deteriorate the processing accuracy.